S. 0. JONES
2452
AND
moved by the reaction of the organic halide with the adjacent atoms of magnesium. If the film is magnesium hydroxide its disappearance on standing might be explained by the reaction with the magnesium bromide from the Grignard equilibrium to produce basic magnesium bromide which is soluble in ether.
Summary (1) Magnesium amalgam electrodes gave zero dark voltage and no light sensitivity with ether solutions of either phenylmagnesium bromide or
E. EMMETREID
Vol. 60
ethylmagnesium bromide. (2) Magnesium electrodes which had been cleaned by reacting with the organic halide gave the same results. (3) Magnesium electrodes which had not been cleaned in this manner showed variable dark voltages and variable photo-voltaic responses. Both of these could be destroyed by adding the organic halide or by allowing the cell to stand for several clays. (4) "Cleaned" magnesium electrodes were made sensitive to light by exposure to oxygen. COI.UNBIA,
MU
._ . .. .-
..
"?CEIVt:D
JUNE
23, 19.78
.
[CONTRIBUTION FROM THE CHEMICAL LABORATORY OF TAB JOHNS
HOPKINSUNIVERSITY]
The Addition of Sulfur, Hydrogen Sulfide and Mercaptans to Unsaturated Hydrocarbons BY S. 0. JONES'
AND
'There have been many investigations of the action of sulfur and hydrogen sulfide on unsaturated hydrocarbons* and a few on the addition of mercaptans3 but so many points have not been cleared up that further study seemed desirable. Curiously enough the end-products are much the same whether an unsaturated hydrocarbon is treated with sulfur, hydrogen sulfide or a mercaptan. Thus with ethylene, sulfur gives hydrogen sulfide which reacts with more ethylene to form ethyl mercaptan which then adds to more ethylene to form ethyl sulfide. Our results help to explain the presence of ethyl, i-propyl and other mercaptans and the corresponding sulfides in petroleum distillates but do not account for the presence of methvl mercaptan and methyl sulfide. The Action of Sulfur.-Quite different results are obtained from the reaction with sulfur according to the conditions and whether free sulfur or a compound which readily liberates sulfur is used. When ethylene was passed over pyrites at 350' about 1% of thiophene was isolated along with hydrogen s a d e and ethyl mercaptan, while when it was bubbled through sulfur at 325' much hydrogen sulfide was formed dong with 3% of ethyl mercaptan and small amounts of carbon disulfide and ethyl suEde. We found it advan(1) Taken from the Ph. D . dissertation of S. 0. Jones, R. J . Reynolds Tobacco Co. Fellow, The Johns Hoplrins University, June, 1936. (2) Mdlhe and Renaudie, Compt. rend., 196, 891 (1932); Duffey, Snow and Keyes, Ind. Eng. Chem., 1 6 , 9 1 (1934). (3) Posner, Bcr , 86, 646 (1905)' Nicolet. THISJ O I T R N A L , 67, 1008 (1935)
E. EMMET REID
tageous to use ethyl tetrasulfide as a sulfur donor. This is a liquid which mixes well with organic compounds and decomposes on heating, giving off what may be assumed to be atomic sulfur. The proportions were calculated on the basis of the tetrasulfide going down to the disulfide. A noteworthy difference is that with it, appreciable yields of the cyclic sulfides were obtained. When ethylene was bubbled slowly through ethyl tetrasulfide kept a t about 150°, the main product isolated was ethyl mercaptan with some ethyl sulfide and in addition some ethylene sulfide. The results of heating several hydrocarbons in a bomb with ethyl tetrasulfide are given in Table I. TABLEJ Hydrocarbons with Et&, 10 hrs. at 180' --
IIydrocarboit
Ethylene Propylene Heptene-1 Octene- I Cyclohexeue
Mercaptan
Yields of r d u c t s , Surfide
5
1s
ti
20
31 15
80 19 b
8
The mercaptans, except from ethylene, and sulfides were all secondary. The Addition of Hydrogen Sulfide.-The addition of hydrogen sulfide was effected by heating in the bomb for ten hours at 180'. Sulfur was added as a catalyst for without it there was little if any addition. The results are given in Table 11. The sulfur is found on the secondary or tertiary carbon atom in accordance with Markownikow's rule.
Oct., 1938
ADDITION OF SULFUR AND SULFIDES TO UNSATURATED HYDROCARBONS
2453
were placed 0.25 g. of p-thiocresol and 0.4 cc. of tridecene. The p-thiocresol had been distilled recently in vacuo and the tridecene had just Hydrocarbon Mercaptan Sulfide been distilled over sodium. To the first tube 11 80 Ethylene 7 90 Propylene was added a trace of ascaridole, to the second a 23 6 &Butylene trace of sulfur and nothing to the third. After 9 35 Octene-1 the usual heating the product in the first tube was 7 5 Cyclohexene solid and on recrystallization gave 0.3 g. which The addition takes place according to Mar- melted at 39.9', the melting point of p-thiocresyl kownikow's rule. In all cases the mercaptan that n-tridecyl sulfide made from n-tridecyl bromide is first formed adds to a second molecule of the in the usual way. From the liquid products hydrocarbon to form the sulfide. In the case of in the other two tubes it was possible to isolate the simple unsaturates this second reaction must 0.01 and 0.08 g., respectively, of the sulfide meltbe rapid as compared to the first addition as little ing at the same point. In a number of experiments the products were of the mercaptans is left over. &Butyl and cyclohexyl mercaptans evidently do not add so readily identified by their boiling points and by oxidation to known solid sulfones but for positive proof of to the hydrocarbons. The Addition of Mercaptans.-The unex- structure unsaturated hydrocarbons6 and merpected observation was made in the course of our captans were chosen that would give known crysexperiments that peroxides influence the mode of talline sulfides which previously had been preaddition of mercaptans to unsaturates just as pared from the potassium salt of the mercaptans Kharasch4 found that they influence the addition and the normal alkyl bromides.6 The tubes were of hydrogen bromide. When we heated ethyl of 2-cc. capacity and the hydrocarbon was in mercaptan with propylene we obtained ethyl i- slight excess. The heating was for ten hours and propyl sulfide, but with octylene the product was 180'. The results given in Table I11 show conethyl n-octyl sulfide. The propylene had never clusively that the abnormal addition took place been exposed to the air while the octylene had been with these hydrocarbons which had been exposed stored for some time in a partly filled bottle and to air for some weeks. In another series tridecylene was added to gave a strong test for peroxides. By adding ethyl mercaptan to propylene in the presence of dimercaptan~.~The results are given .in Table added peroxides, we obtained ethyl n-propyl sul- IV. In one experiment lauryl mercaptan was added fide. It has been observed by Posner and Nicolet3 to allyl lauryl sulfide CI2Hz6SCH2CH=CH2and m.~ Zp.H ~ ~ , that thiophenol and p-thiocresol add to unsatu- the product was C B H ~ ~ ( C H ~ ) ~ S C rates contrary to Markownikow's rule. We have 4 7 O , proved by melting point and mixed melting verified this in a large number of cases, but by point to be identical with that from lauryl brousing freshly distilled thiophenol and p-thiocre- mide and trimethylene mercaptan. sol we were able to reverse the mode of addition. Experimental Kharasch4 observed that p-thiocresol was not Ten moles of ethylene bubbled at the rate of 50 cc. per effective as an anti-oxidant unless it was freshly distilled. It appears that only very small amounts minute through a 25-cm. layer of sulfur in a vertical tube kept at 325' gave much hydrogen sulfide. The 25 cc. of of peroxides such as are usually present in the condensate gave 15 g. of ethyl mercaptan, b. p. 34-37', hydrocarbon or in the p-thiocresol itself are suf- Hg(SEt)s, m. p. 76', 2 g. of carbon disulfide and 3 g. of ficient to influence the addition of mercaptans ethyl sulfide, b. p. 91-92', Et&HgCle, m. p. 76.5". Five while for hydrogen bromide much larger amounts moles passed at the rate of 20 cc. per minute through a 20are required. In the absence of catalysts scarcely cm. column of ethyl tetrasulfide at 140-150" gave 30 g. of condensate, largely ethyl sulfide but containing 10 g. of any addition takes place even on heating for ethyl mercaptan Hg(SEt)*,m. p. 76', and 1.5 g. of ethylene twenty-four hours at 180'. Sulfur catalyzes the b. p. 54-57', S calcd. 53.36, found 53.09 and 53.12. normal addition and peroxides the abnormal. (5) Prepared by Kozacik and Reid, ibid., 60, 2436 (1938). It is difficult to suppress the abnormal addition (6)The alkyl bromides were those described by Meyer and Reid, 66, 1574 (1933). entirely. Into each of 3 tubes of 2-cc. capacity ibid., (7) Hall and Reid, unpublished results. TABLEI1 Addition of hydrogen sulfide, 10 hrs. at 180' --Yields of products, %-
(4) Kharasch and Hannum. THIS JOURNAL, 66,712 (1934).
( 8 ) DelCpine. Bull.
SOC.
chim., 788, 03 (1923).
s. 0. JONES AND E.EMMETREID
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MELTINGPOINTS
AND
Vol. 60
TABLE 111 ANALYSES OF SULFIDES OBTAINED BY ADDITION COMPARED WTE THOSE O F SYNTHETIC SULFIDES BY
Un-aturata
Sulfide
CHa( CHz)aCH=CHz CH3(CHi)sCH=CHz CHs( CHZ)ECH=CHZ CH3(CHz)aCH=CH? CHa( CHz)ioCH=CHn CHa( CHz)ioCH=CHz CHs(CHz)ioCH=CHz CH3(CHz)ioCH=CHs CH3(CHz)izCH=CHz CH~(CH~)I~CH=CHI CHa(CH1)13CH=CHz CHB(CHi)izCH=C€Iz CH,(CHz)i4CH=CHi CHa( CHn)irCH=CHs CHa(CHz)i4CH=CH? CH3(CHz)irCH=CHz C€Is( CHi)isCH=CHs CH3(CHz)isCH=CHs CH3(CHz)lsCH=CHx CH3(CHz)isCH=CHz TABLEIV MELTINGPOINTS AND ANALYSES OF SULFIDES OBTAINED BY ADDITION OF TRIDECENE TO DIMERCAPTANS AND MELTINGPOINTSOF SYXTFIETIC SULFIDES. R = n-ClaHz7 S y n - By adSulfur, 5; Mercaptan
HS(CHz)zSH HS(CHn)aSH HS(CH9)dSH HS(CH2)bSH HS(CHz)sSH HS(CHz).SH HS(CHi)sSH HS(CH2)sSH HS(CHz)ioSH HS(CH2)iiSH HS(CHz)izSH HS(CHa)isSH
Sulfide
RS(CHz)zSR RS(CH?):SR RS(CHz),SR KS(CHd1SR RS(CH2)sSR RS(CH2);SK RS(CH2)aSK RS(CHz)oSR RS(CH*)ioSR RS(CHz)iiSR RS(CH.)IISII RS(CH2)isSK
thetic dition Calcd. Found 63.9 13 98 13.69 13.75 64 13 37 13.30 13 36 $3 53
56.2 56.2 13.17 57.4 57.3 12 80 39.2 39.2 12 45 ti0 4 60.4 12 13 61.2 59.4 11.81 63.8 63.8 1 1 51 64.2 6 4 . 2 11.23 10 06 66.6 65 67.0 65.5 10.71 0.31 73.6 73
13.47 13.10 12.70 12.65 12.50 12 40 1 2 . I U 12.09 11.91 11.09 11.62 11.44 11.01 11.19 10.80 10.74 11.01 10 89 9.21 0 . 2 5
This was identical with a prcparation by thc method of DelCpine. All other experiments unless otherwise stated were made by heating in a steel bomb for ten hours at 180'. From 30 g. of propylene and 45 g. of ethyl tetrasulfide we obtained: 1 g. of carbon disulfide, 3 g. of i-PrSH, Hg(i-PrS)n, ni. p. 62'; 21 g. of i-PrZS, b. p. 118-121'; oxidized to sulfone, m. p. 36.4'; z-PrzSO2, m. p. 36",@and 10 g. of cyclic propylene sulfide, S calcd. 43.26, found 43.14. Under the same conditions, substituting sulfur for the ethyl tctrasulfide, the same products were foundexcept that there was none of the cyclic suliide. Isobutylene, 14 g., and 23 g. of ethyl tetrasuffide in the bomb eight hours at 160' gave 1 g. of carbon disulfide, 5 g. of ethyl disulfide and a mixture of unsaturated hydrocarbons from which no sulfur compounds could be isolated. From 27 g. of heptene-1 and 15 g. of Et&, we obtained 5 g. of carbon disulfide, 3 g. of ethyl disulfide, and 10.5 g.. (9) Delepine, Com9f. r e n d . , 172, 1.58 (1921 1
synthetic addition M . p , ' C . hl. p., OC
7 -
Calcd.
33.8 20.8 46.8 37.2 43.8 40.2 54.6 39.2
